JP7265505B2 - Radiation image acquisition system and imaging unit - Google Patents

Description

The present disclosure relates to imaging units and radiographic image acquisition systems.

Some devices or systems are known that irradiate an object with X-rays, convert the X-rays that have passed through the object into scintillation light with a scintillator, and detect the scintillation light with a detector. For example, the system described in Patent Document 1 includes an opaque scintillator and captures scintillation light output from the input surface of the scintillator (the surface on which X-rays are input). One form of this system includes a transport device that transports an object in the transport direction, and uses a line scan camera to capture an image according to the transport speed of the object.

On the other hand, the device described in Patent Document 2 includes first imaging means for imaging scintillation light output from the input surface (front surface) of the scintillator, and output from the surface (back surface) opposite to the input surface of the scintillator. and second imaging means for imaging the scintillation light. One of the first and second imaging means collects the scintillation light output in the normal direction of the front surface or the back surface, and the other of the first and second imaging means collects the scintillation light output in the normal direction of the front surface or the back surface. It collects scintillation light output in an inclined direction. US Pat. No. 6,200,000 describes a system for dental radiographic imaging. This system also obtains a radiation image by condensing light from a scintillation plate (or scintillation screen) with a lens and detecting it with a CCD.

WO2017/056680 JP 2012-154734 A Japanese Patent Publication No. 2000-510729

In the system described in Patent Document 1, by observing the input surface using an opaque scintillator, it is possible to identify the shape and the like of an object made of light elements such as plastic. A form using a transport device and a line scan camera can acquire a radiographic image at a higher speed. However, when using a transport device, the image acquired by the line scan camera may be blurred due to the varying magnification in different parts of the object. On the other hand, Patent Documents 2 and 3 describe that a mirror that reflects scintillation light may be installed in order to capture an image of scintillation light output from the input surface of the scintillator. These mirrors are placed facing the input surface, but the mirrors can affect the X-rays transmitted through the object. For example, the effect can occur that X-rays are absorbed by the mirror. This effect can make it difficult to acquire radiographic images with high sensitivity.

The present disclosure is an imaging unit that can prevent a radiographic image from being blurred even for a transported object, and can eliminate the influence of a mirror on radiation even when scintillation light output from the input surface of a scintillator is detected. and a radiographic image acquisition system are described.

One aspect of the present disclosure is an imaging unit for acquiring a radiographic image of an object that is transported in a transport direction on a predetermined transport route, the imaging unit having a wall that faces the transport route. , a housing having a slit formed in the wall for passing radiation, a scintillator installed in the housing and having an input surface for inputting the radiation that has passed through the slit, and a scintillator installed in the housing and output from the input surface and a line scan camera installed in the housing for detecting the scintillation light reflected by the mirror, the scan direction corresponding to the transport direction and the scan direction orthogonal to the scan direction a line scan camera having a line direction and a line direction, wherein the scintillator is arranged such that the input surface is parallel to the transport direction and parallel to the line direction; It is located outside the connecting irradiation area.

In this imaging unit, the radiation that has passed through the object conveyed on the conveying path passes through the slit formed in the wall of the housing. A scintillator, one or more mirrors, and a line scan camera are installed in the housing, and the devices required for imaging are unitized. Radiation entering the housing is input to the input surface of the scintillator, and scintillation light is output from the input surface. In regions close to the input face of the scintillator, relatively low energy radiation is converted. Therefore, the line scan camera can acquire radiation images with excellent sensitivity to low-energy radiation. This is advantageous, for example, for the detection of substances consisting of light elements. Since the input surface of the scintillator is parallel to the transport direction and parallel to the line direction of the line scan camera, the magnification is It does not change. Therefore, blurring of the radiographic image is prevented. Furthermore, since the mirror is located outside the irradiation area of the radiation, the radiation that has passed through the object is input to the input surface of the scintillator without passing through the mirror. This eliminates the influence of the mirror on the radiation. As a result, this imaging unit makes it possible to acquire a radiographic image of an object clearly and with high sensitivity.

In some aspects, the mirror comprises a first mirror positioned superimposed on a normal to the input surface, the first mirror forming an acute angle between the reflective surface of the first mirror and the input surface. However, the line scan camera detects scintillation light emitted in the direction normal to the input surface. When scintillation light output in a direction inclined with respect to the normal direction of the input surface is detected, an image is oblique (perspective) due to the difference in magnification of the lens. In that case, the image may be blurred. In contrast, according to the above configuration, the first mirror reflects the scintillation light output in the normal direction of the input surface, and the scintillation light is detected by the line scan camera. Therefore, the line scan camera can acquire an image without perspective. The radiographic image is prevented from being blurred.

In some aspects, the slit is located between the scintillator and first mirror and the linescan camera in the transport direction. This configuration allows the radiation to be successfully introduced within the acute angle between the scintillator and the first mirror. That is, the illuminated area can be well formed within the acute angle range between the scintillator and the first mirror. On the other hand, it is easy to secure the optical path length required for the line scan camera.

In some embodiments, an acute angle is an angle within the range of 40 degrees to 50 degrees. According to this configuration, the scintillation light output in the normal direction of the input surface is reflected by the first mirror and detected by the line scan camera at an inclination angle of 10 degrees or less with respect to the transport direction. Therefore, the housing can be elongated in the transport direction, and the line scan camera can be installed in the housing. The entire imaging unit has a slim shape along the transport path, and the compactness of the imaging unit is achieved.

In some aspects, the slit is positioned upstream or downstream of the scintillator in the transport direction. According to this configuration, it is easy to form an irradiation area while arranging the mirror at a desired position so that the mirror does not interfere with the radiation irradiation area.

In some embodiments, the optical axis of the line scan camera is parallel to the transport direction. For each element, the input face of the scintillator is parallel to the transport direction, as described above. This configuration eliminates the need for complicated adjustments related to angles. For example, it becomes easy to adjust the optical axis of the line scan camera and adjust the distance between the mirror and the lens according to the viewing angle associated with the lens focal length of the line scan camera.

In some aspects of the imaging unit, the imaging unit further comprises a second line scan camera installed within the housing for detecting scintillation light output from a surface opposite to the input surface. Relatively high-energy radiation is converted in regions near the surface of the scintillator opposite the input surface. A line scan camera acquires a low energy radiation sensitive radiographic image, while a second line scan camera simultaneously acquires a high energy radiographic image. This realizes a dual-energy imaging unit. Such a scintillator double-sided observation method can obtain a larger energy difference than a conventional dual energy unit, and improves foreign matter detection performance. This imaging unit is excellent in the discrimination performance of substances composed of light elements, for example.

As another aspect of the present disclosure, a radiation source that outputs radiation toward an object, a transport device that transports the object in a transport direction, and the transport device so that the irradiation area includes the transport path of the transport device: and any one of the above imaging units attached to the radiographic image acquisition system. In this radiographic image acquisition system, by including any one of the imaging units described above, blurring of the radiographic image is prevented, and the influence of the mirror on radiation is eliminated. Therefore, this radiographic image acquisition system makes it possible to acquire a radiographic image of an object clearly and with high sensitivity.

Yet another aspect of the present disclosure is a radiographic image acquisition system for acquiring a radiographic image of a target, comprising: a radiation source that outputs radiation toward the target; a transport device that transports the target in a transport direction; A scintillator having an input surface for inputting radiation transmitted through an object transported by the transport device, one or more mirrors for reflecting scintillation light output from the input surface, and detecting the scintillation light reflected by the mirror. a line scan camera having a scan direction corresponding to the transport direction and a line direction orthogonal to the scan direction, wherein the scintillator has an input surface parallel to the transport direction and parallel to the line direction. and the mirror is located outside the illumination area between the focal point of the radiation source and the input surface of the scintillator.

In this radiographic image acquisition system, an object conveyed by a conveying device is irradiated with radiation from a radiation source. Radiation transmitted through the object is input to the input surface of the scintillator. Then, scintillation light is output from the input surface. In regions close to the input face of the scintillator, relatively low energy radiation is converted. Therefore, the line scan camera can acquire radiation images with excellent sensitivity to low-energy radiation. This is advantageous, for example, for the detection of substances consisting of light elements. Since the input surface of the scintillator is parallel to the transport direction and parallel to the line direction of the line scan camera, the magnification is It does not change. Therefore, blurring of the radiographic image is prevented. Furthermore, since the mirror is located outside the irradiation area of the radiation, the radiation that has passed through the object is input to the input surface of the scintillator without passing through the mirror. This eliminates the influence of the mirror on the radiation. As a result, this radiographic image acquisition system makes it possible to acquire a radiographic image of an object clearly and with high sensitivity.

In some aspects, the mirror comprises a first mirror positioned superimposed on a normal to the input surface, the first mirror forming an acute angle between the reflective surface of the first mirror and the input surface. However, the line scan camera detects scintillation light emitted in the direction normal to the input surface. When scintillation light output in a direction inclined with respect to the normal direction of the input surface is detected, an image is oblique (perspective) due to the difference in magnification of the lens. In that case, the image may be blurred. In contrast, according to the above configuration, the first mirror reflects the scintillation light output in the normal direction of the input surface, and the scintillation light is detected by the line scan camera. Therefore, the line scan camera can acquire an image without perspective. The radiographic image is prevented from being blurred.

In some aspects, the radiation source is positioned such that the focal point is located between a first virtual plane containing the reflective surface of the first mirror and a second virtual plane containing the input surface. This arrangement allows the radiation from the radiation source to be successfully introduced within the acute angle between the scintillator and the first mirror. That is, the illuminated area can be well formed within the acute angle range between the scintillator and the first mirror.

In some embodiments, an acute angle is an angle within the range of 40 degrees to 50 degrees. According to this configuration, the scintillation light output in the normal direction of the input surface is reflected by the first mirror and detected by the line scan camera at an inclination angle of 10 degrees or less with respect to the transport direction. Therefore, it is easy to install a line scan camera along the conveying device. The entire image pickup unit has a slim shape along the conveying device, and the image pickup unit can be made compact.

In some aspects, the illuminated area is formed upstream or downstream of the scintillator in the transport direction. According to this configuration, it is easy to form an irradiation area while arranging the mirror at a desired position so that the mirror does not interfere with the radiation irradiation area.

In some embodiments, the optical axis of the line scan camera is parallel to the transport direction. As noted above, the input surface of the scintillator is parallel to the transport direction. This configuration eliminates the need for complicated adjustments related to angles for each element. For example, it becomes easy to adjust the optical axis of the line scan camera and adjust the distance between the mirror and the lens according to the viewing angle associated with the lens focal length of the line scan camera.

Some aspects of the radiological image acquisition system further comprise a second linescan camera that detects scintillation light output from a surface opposite the input surface. Relatively high-energy radiation is converted in regions near the surface of the scintillator opposite the input surface. A line scan camera acquires a low energy radiation sensitive radiographic image, while a second line scan camera simultaneously acquires a high energy radiographic image. This realizes a dual energy imaging unit. Such a scintillator double-sided observation method can obtain a larger energy difference than a conventional dual energy unit, and improves foreign matter detection performance. This radiographic image acquisition system is excellent in discrimination performance for substances composed of light elements, for example.

Aspects of the present invention prevent radiographic image blurring and eliminate the effects of mirrors on radiation. As a result, a radiographic image of the object can be acquired clearly and with high sensitivity.

FIG. 1 is a diagram showing a schematic configuration of a radiographic image acquisition system according to the first embodiment of the present disclosure. 2 is a cross-sectional view showing the internal configuration of the imaging unit in FIG. 1; FIG. 2 is a diagram showing the positional relationship among a radiation source, an irradiation region, a scintillator, a first mirror, and a line scan camera in the radiographic image acquisition system of FIG. 1; FIG. FIG. 4 is a diagram showing the positional relationship between a slit formed in a housing, a scintillator, and a first mirror; FIG. 5(a) is a diagram showing an irradiation area when a radiation source is installed obliquely, and FIG. 5(b) is a diagram showing an irradiation area when a radiation source with a wide irradiation angle is installed. FIG. 6(a) is a diagram showing the arrangement of scintillators in the first embodiment, FIG. 6(b) is a diagram showing the arrangement of scintillators in the reference embodiment, and FIG. 6(c) is a radiographic image obtained in FIG. 6(a) , and FIG. 6(d) is a diagram showing a radiographic image obtained in FIG. 6(b). FIG. 7(a) is a diagram showing a configuration in which a line scan camera is installed in the normal direction of the input surface, FIG. 7(b) is a diagram showing a configuration in which a line scan camera is installed in a diagonal direction of the input surface, and FIG. FIG. 7(c) shows a radiographic image obtained in FIG. 7(a), and FIG. 7(d) shows a radiographic image obtained in FIG. 7(b). FIG. 8(a) is a diagram showing the arrangement of the radiation source in the reference embodiment, FIG. 8(b) is a diagram showing the interference between the irradiation region and the first mirror in FIG. 8(a), and FIG. 8(c) is the first embodiment. It is a figure which shows the position of the irradiation area|region in a form. It is a figure showing a schematic structure of a radiographic image acquisition system concerning a 2nd embodiment of this indication. It is a figure which shows the imaging unit which concerns on the 1st modification of 2nd Embodiment. It is a figure which shows the imaging unit which concerns on the 2nd modification of 2nd Embodiment. FIG. 11 is a diagram showing an imaging unit according to a third modification of the second embodiment; FIG. It is a figure which shows the radiographic image acquisition system based on the 1st modification of 1st Embodiment. FIG. 5 is a diagram showing a modified example of an imaging unit in the radiation image acquisition system of FIG. 4; It is a figure which shows the 1st modification of a line scan camera. 16(a) and 16(b) are diagrams respectively showing a second modification of the line scan camera. FIG. 10 is a diagram showing a modification of the sensor of the line scan camera; It is a figure which shows an example of the movement mechanism of a 1st mirror. 19(a) and 19(b) are diagrams respectively showing an example of a replaceable first mirror unit. 20(a) and 20(b) are diagrams showing an example of a mechanism for moving the scintillator. It is a figure which shows the modification of a scintillator. 22(a) and 22(b) are diagrams showing an example of a slit position changing mechanism. It is a figure which shows an example of the position adjustment mechanism of a line scan camera.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, each drawing is created for the purpose of explanation, and is drawn so as to particularly emphasize the parts to be explained. Therefore, the dimensional ratio of each member in the drawing does not necessarily match the actual one.

As shown in FIG. 1, a radiographic image acquisition system 1 of the first embodiment is a device for acquiring a radiographic image of an object A. As shown in FIG. Object A contains, for example, a substance consisting of a light element. The radiation image acquisition system 1 is applied to fields such as food inspection and battery inspection, for example. In the field of food inspection, for example, the presence or absence of foreign matter is inspected. The radiographic image acquisition system 1 has a unique configuration, which will be described later, and is particularly excellent in discrimination performance for substances composed of light elements. Such substances include, for example, food waste, hair, vinyl, insects, bones in meat, and the like. The radiographic image acquisition system 1 is applied, for example, to inline X-ray examination.

The radiation image acquisition system 1 includes a radiation source 2 that outputs radiation such as white X-rays toward an object A, a transport device 20 that transports the object A in a predetermined transport direction D, and a a scintillator 6 for generating scintillation light in response to input of radiation transmitted through an object A, a line scan camera 3 for detecting scintillation light output from a radiation input surface 6a of the scintillator 6; and a computer 10 which controls several functions of and produces radiographic images. Thus, the radiographic image acquisition system 1 is a scintillator surface observation type X-ray imaging system. The radiographic image acquisition system 1 is excellent in low-energy X-ray sensitivity.

The radiation source 2 outputs cone beam X-rays from an X-ray emission unit. The radiation source 2 has a focal point 2a of cone-beam X-rays. The radiation source 2 may be, for example, a microfocus X-ray source or a millifocus X-ray source. The X-rays emitted by the radiation source 2 form a radiation flux. The area in which this radiation flux exists is the output area 14 of the radiation source 2 (see FIG. 3). In the radiographic image acquisition system 1 , X-rays within the irradiation region 12 , which are part of the X-rays within the output region 14 , are input to the input surface 6 a of the scintillator 6 . That is, the irradiation area 12 is an area that is included in the output area 14 and narrower than the output area 14 . The irradiation area 12 includes a central axis L located at its center.

The conveying device 20 has, for example, a belt conveyor 21 that moves on a circular track, and an object A is placed or held on a conveying surface 21 a of the belt conveyor 21 . The belt conveyor 21 is a transport stage or a transport section. The conveying device 20 includes a drive source (not shown) that drives the belt conveyor 21 . The conveying device 20 is configured to convey the object A in the conveying direction D at a constant speed. In other words, the object A is transported on the predetermined transport route P by the transport device 20 . In this embodiment, the transport direction D is horizontal. Further, the transport path P is linear, and the direction in which the transport path P extends is parallel to the transport direction D. As shown in FIG. The transport timing and transport speed of the object A in the transport device 20 are set in advance and controlled by the controller 10 a of the computer 10 .

Note that the radiographic image acquisition system 1 is compatible with all types of transport devices 20 . For example, the conveying direction D and the conveying path P may be horizontal, but may be inclined with respect to the horizontal. The conveying path P may not be linear, and may be curved, for example. In that case, the transport direction D may be a tangent to a portion of the transport path P that overlaps the irradiation area 12 . The transport device 20 may not have a physical transport surface 21a. For example, the conveying device 20 may convey the object A in a state in which it is lifted by air. Alternatively, the transport device 20 may transport the object A by releasing the object A into the air. In that case, the transport path P may be parabolic, for example.

The transport device 20 is not limited to the form having the belt conveyor 21 . The transport device 20 may have, for example, a roller conveyor including a plurality of rollers. Since roller conveyors do not have belts, the influence of belts can be eliminated. A gap (slit-shaped opening) is formed between the rollers, which is also advantageous compared to the belt conveyor. Using a roller conveyor reduces x-ray attenuation caused by the belt. Considering the arrangement of the radiation source 2 and the arrangement of the irradiation area 12 (oblique irradiation), which will be described later, the roller conveyor can be effectively used. A roller conveyor is a transport means suitable for the radiographic image acquisition system 1 in which low-energy X-ray sensitivity is emphasized. Two or more belt conveyors may be installed in the conveying direction, and X-rays may be irradiated from the gaps between these belt conveyors. In this form, while using the belt conveyor, the influence of the belt can be eliminated as in the case of the roller conveyor.

As shown in FIGS. 1 to 3, the radiographic image acquisition system 1 includes an imaging unit 30 installed along the transport device 20. As shown in FIGS. The imaging unit 30 is, for example, attached to the transport device 20 and fixed to the transport device 20 . The imaging unit 30 is attached so as not to interfere with the circulation of the belt conveyor 21 . The same applies when the transport device 20 is a roller conveyor. The imaging unit 30 is positioned with some clearance from the transport so as not to interfere with the movement of the transport, such as a belt or roller conveyor.

The imaging unit 30 has a rectangular parallelepiped housing 13 . The housing 13 is made of, for example, a material capable of shielding X-rays. The housing 13 is a so-called dark box. Housing 13 may be made of aluminum or iron, for example. The housing 13 may include a protective material, and lead may be used as the protective material. The housing 13 has a shape elongated in the transport direction D. As shown in FIG. The housing 13 includes a top wall portion 13a and a bottom wall portion 13b facing in the vertical direction, a first side wall portion 13c and a second side wall portion 13d facing in the transport direction D, and a horizontal detection width orthogonal to the transport direction D. It includes a third side wall portion 13e and a fourth side wall portion 13f (see FIG. 4) facing in the direction. The imaging unit 30 has a very small first side wall portion 13c and a second side wall portion 13d of the housing 13, and is a compact device along the conveying device 20. As shown in FIG. The transport direction D is parallel to the x direction parallel to the plane of the paper shown in the drawing. The detection width direction is parallel to the y-direction perpendicular to the plane of the paper shown in the drawing. The vertical direction is parallel to the z-direction parallel to the plane of the paper shown in the drawing.

The upper wall portion (wall portion) 13 a is arranged to face the transport path P of the transport device 20 . In other words, the upper wall portion 13 a is closest to the conveying device 20 among the six wall portions of the housing 13 . This upper wall portion 13 a may be attached to the conveying device 20 .

The imaging unit 30 is configured to capture an image of the scintillation light output from the input surface 6a of the scintillator 6 in the normal B direction of the input surface 6a. Therefore, the imaging unit 30 includes a first mirror 7 that reflects the scintillation light output in the normal B direction of the input surface 6a. That is, the imaging unit 30 includes only one first mirror 7 as a mirror. The first mirror 7 is arranged at a position overlapping the normal line B of the input surface 6a so that the reflecting surface 7a faces the input surface 6a obliquely.

A scintillator 6 , a first mirror 7 , and a line scan camera 3 are installed inside the housing 13 . The scintillator 6 , the first mirror 7 and the line scan camera 3 are fixed inside the housing 13 . The scintillator 6 and the first mirror 7 are arranged near the first side wall portion 13c. The line scan camera 3 is arranged near the second side wall portion 13d. The scintillator 6 is held, for example, by a scintillator holder 8 and arranged, for example, horizontally. The first mirror 7 is held, for example, by a mirror holder 9 and arranged so as to be inclined with respect to the horizontal.

The scintillator 6 is a tabular wavelength conversion member. The scintillator 6 has a rectangular shape elongated in the detection width direction (y direction) (see FIG. 4). _The scintillator 6 is _made of, for example, _Gd2O2S :Tb, _Gd2O2S :Pr _{, CsI} :Tl, _{CdWO4 , CaWO4} , _{Gd2SiO5 :} Ce, _{Lu0.4Gd1.6SiO5} , _{Bi4Ge3O 12} , _Lu2SiO5 :Ce, _Y2SiO5 , _YAlO3 :Ce, _Y2O2S :Tb, _YTaO4 :Tm, _YAG :Ce, YAG: _Pr , and the like _. The thickness of the scintillator 6 is set to an appropriate value depending on the energy band of radiation to be detected in the range of several μm to several mm. The scintillator 6 converts the X-rays that have passed through the object A into visible light. Relatively low energy X-rays are converted at the input surface 6a of the scintillator 6 and output from the input surface 6a. X-rays with relatively high energy are converted by the back surface 6b of the scintillator 6 and output from the back surface 6b. In this embodiment, the scintillator holder 8 is open upward, exposing the input surface 6a of the scintillator 6 . On the other hand, the back side 6b can be closed, but it can also be exposed. The scintillator 6 may be composed of a single scintillator, or may be a combination of two scintillators such as pasted together. When combining two scintillators, a plate or film having light blocking or reflecting properties may be sandwiched between the two scintillators. The types of the two scintillators may be the same or different.

The first mirror 7 is, for example, a mirror made of aluminum-deposited glass or mirror-finished metal. The first mirror 7 has a rectangular shape elongated in the detection width direction (y direction) (see FIG. 4). The first mirror 7 has a reflecting surface 7a having a sufficient area to reflect the scintillation light output in the normal B direction from the input surface 6a. The first mirror 7 forms an acute angle between the reflecting surface 7a and the input surface 6a of the scintillator 6, for example. Here, the fact that the first mirror 7 forms an angle with respect to the input surface 6 a does not mean that the first mirror 7 is close to the scintillator 6 . Although the first mirror 7 may be close to the scintillator 6 , the first mirror 7 may be separated from the scintillator 6 . When the first mirror 7 is separated from the scintillator 6, the angle is defined by the extended surface of the reflecting surface 7a and the extended surface of the input surface 6a. The first mirror 7 reflects the scintillation light output in the normal B direction of the input surface 6a.

The above acute angle is preferably an angle within the range of 40 degrees or more and 50 degrees or less. More preferably, the acute angle is 45 degrees. The acute angle may be determined based on the placement of the radiation source 2 and the position of the slit 15, which will be described later. The placement of the line scan camera 3 may be appropriately adjusted according to the magnitude of the acute angle. Another mirror or mirrors may also be installed depending on the magnitude of the acute angle.

The line scan camera 3 takes images as the object A moves. The line scan camera 3 is a lens coupling type having a lens portion 3a for condensing the scintillation light output from the input surface 6a of the scintillator 6 and a sensor portion 3b for detecting the scintillation light condensed by the lens portion 3a. is a detector of The lens portion 3a includes one lens, which is focused on the input surface 6a of the scintillator 6. FIG. The sensor section 3b includes an image sensor 3c. The image sensor 3c is, for example, an area image sensor capable of TDI (time delay integration) driving. Image sensor 3c is, for example, a CCD area image sensor.

The image sensor 3c has a structure in which an array of elements in which a plurality of CCDs are arranged in a row in the pixel direction is arranged in multiple stages in the direction of integration corresponding to the direction in which the object A moves. As shown in FIG. 2, the line scan camera 3 has a scanning direction d1 corresponding to the transport direction D of the object A and a line direction d2 perpendicular to the scanning direction d1. This scanning direction d1 is the integration direction described above, and is parallel to the z direction in the figure. The line direction d2 is the above pixel direction and is parallel to the y direction in the figure. The scanning direction d1 is a direction converted from the conveying direction D via the first mirror 7 . In this embodiment, the scanning direction is changed from the transport direction D by 90 degrees.

The image sensor 3c is controlled by the controller 10a so as to perform charge transfer as the object A moves. That is, the image sensor 3c performs charge transfer on the light receiving surface 3d in synchronization with the movement of the object A by the transport device 20. FIG. As a result, a radiographic image with a good S/N ratio can be obtained. When the image sensor 3c is an area image sensor, the control unit 10a of the computer 10 controls the radiation source 2 and the line scan camera 3 so that the radiation source 2 is turned on in time with the imaging timing of the line scan camera 3. It may be configured to allow An encoder may be provided on the stage and the line scan camera 3 may be controlled by a signal from the encoder.

When the acute angle between the reflecting surface 7a of the first mirror 7 and the input surface 6a of the scintillator 6 is 45 degrees, the optical axis F (see FIG. 3) of the lens portion 3a of the line scan camera 3 is aligned with the transport direction D parallel to The line scan camera 3 detects scintillation light output in the normal B direction of the input surface 6a.

The scintillator 6 is arranged such that the input surface 6a is parallel to the transport direction D and parallel to the line direction d2. That is, the input surface 6a of the scintillator 6 is parallel to the xy plane.

As shown in FIGS. 1 to 4, the upper wall portion 13a of the housing 13 is formed with a slit 15 through which the X-rays output from the radiation source 2 pass. As shown in FIG. 4, the slit 15 has a rectangular shape elongated in the detection width direction (y direction). The slit 15 includes a rectangular peripheral edge 15a. As shown in FIG. 3, the input surface 6a of the scintillator 6 receives X-rays in the irradiation area 12 that have passed through the slit 15. As shown in FIG.

To explain the slit 15 and the irradiation area 12 in more detail, as shown in FIG. there is X-rays in the remaining area do not enter the housing 13 . That is, the slit 15 defines the irradiation area 12 . The central axis L of the irradiation area 12 passes through the center of the slit 15 . The irradiation area 12 is defined as an area (quadrangular pyramid-shaped area) that linearly connects the peripheral edge 15 a of the slit 15 and the input surface 6 a of the scintillator 6 . In other words, the irradiation region 12 is defined as a region connecting the focal point 2a of the radiation source 2 and the input surface 6a of the scintillator 6 in a straight line. Here, the "input surface 6a of the scintillator 6" means only a region that effectively works to output scintillation light. For example, of the entire rectangular input surface 6a, the area covered by the scintillator holder 8 is not included in the “input surface 6a of the scintillator 6” for defining the irradiation area 12. FIG.

1 and 2, the slit 15 is positioned between the scintillator 6 and the first mirror 7 and the line scan camera 3 in the transport direction D. As shown in FIGS. The radiation source 2 is arranged such that the focal point 2a is positioned between a first virtual plane P1 including the reflecting surface 7a of the first mirror 7 and a second virtual plane P2 including the input surface 6a of the scintillator 6 ( See Figure 2). Also, the slit 15 is positioned downstream of the scintillator 6 in the transport direction D. As shown in FIG. As shown in FIG. 3, the first mirror 7 is positioned outside the X-ray irradiation area 12 . In other words, the first mirror 7 is installed at a position and attitude (including inclination) that does not interfere with the irradiation area 12 . The first mirror 7 is arranged so as to be inclined with respect to the normal B of the input surface 6 a so that the reflecting surface 7 a is along the boundary surface of the irradiation area 12 . The scintillation light condensed by the lens portion 3a of the line scan camera 3 traverses the irradiation region 12 in the z direction (normal B direction of the input surface 6a) and then traverses the irradiation region 12 in the x direction (conveying direction D). do.

In addition, the radiation source 2 may be installed in various modes. For example, as shown in FIG. 5(a), a radiation source 2 with a narrow irradiation angle, ie, a narrow output area 14, may be installed obliquely. In this case, the output area 14 may be equivalent to the irradiation area 12 . Alternatively, as shown in FIG. 5B, the radiation source 2 having a wide irradiation angle, ie, a wide output area 14, may be installed vertically. In this case, the central axis of the output area 14 is oriented in the vertical direction (z direction), but the central axis L of the irradiation area 12 intersects the input surface 6 a of the scintillator 6 . The radiation source 2 is arranged on the first virtual plane P1 including the reflecting surface 7a of the first mirror 7, or above the first virtual plane P1 (opposite to the second virtual plane P2). may

The computer 10 has, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input/output interface, and the like. The computer 10 includes a control unit 10a (control processor) for controlling the radiation source 2 and the line scan camera 3, and image processing for creating a radiation image of the object A based on the radiation image data output from the line scan camera 3. and a unit 10b (image processor). The image processing unit 10b receives radiation image data and executes predetermined processing such as image processing on the received radiation image data. A display device 11 is connected to the computer 10 . The image processing unit 10 b outputs the created radiation image to the display device 11 . The control unit 10a controls the radiation source 2 based on the values of the tube voltage and the tube current of the radiation source 2 which are stored by the user's input or the like. The control unit 10a controls the line scan camera 3 based on the exposure time and the like of the line scan camera 3 stored by the user's input and the like. The control unit 10a and the image processing unit 10b may be separate processors or may be the same processor. Further, the computer 10 may be programmed to execute the functions of the control section 10a and the image processing section 10b. The computer 10 may be composed of a microcomputer or an FPGA (Field-Programmable Gate Array).

Next, the operation of the radiographic image acquisition system 1, that is, the radiographic image acquisition method will be described. First, the conveying device 20 is used to convey the object A in the conveying direction D (conveying step). At the same time, radiation such as white X-rays is output from the radiation source 2 toward the object A (radiation output step). Radiation transmitted through the object A is input to the input surface 6a (input step). At this time, since the radiation does not interfere with the first mirror 7, the influence of the first mirror 7 is eliminated. Next, the scintillator 6 converts the radiation into scintillation light (conversion step). The scintillation light output from the input surface 6a is reflected by the first mirror 7 (reflection step). Then, the lens portion 3a of the line scan camera 3 forms an image of the scintillation light on the image sensor 3c (imaging step). The image sensor 3c captures the scintillation light (scintillation image) imaged by the lens unit 3a (imaging step). In this imaging process, charge transfer (TDI operation) is performed in synchronization with the movement of the object A. FIG. The line scan camera 3 outputs radiation image data obtained by imaging to the image processing section 10 b of the computer 10 .

The image processing unit 10b of the computer 10 receives radiation image data, executes predetermined processing such as image processing on the input radiation image data, and creates a radiation image (image creation step). The image processing unit 10 b outputs the created radiation image to the display device 11 . The display device 11 displays the radiation image output from the image processing section 10b. Through the above steps, a radiographic image of the object A is obtained by surface observation.

In the radiation image acquisition system 1 and the imaging unit 30 of the present embodiment, the object A transported by the transport device 20 is irradiated with radiation from the radiation source 2 . Radiation that has passed through the object A passes through a slit 15 formed in the upper wall portion 13 a of the housing 13 . A scintillator 6, a first mirror 7, and a line scan camera 3 are installed in the housing 13, and equipment necessary for imaging is unitized. Radiation that has entered the housing 13 is input to the input surface 6 a of the scintillator 6 . Then, scintillation light is output from the input surface 6a. In the region close to the input surface 6a of the scintillator 6 relatively low energy radiation is converted. Therefore, the line scan camera 3 can acquire radiation images with excellent sensitivity to low-energy radiation. This is advantageous for the detection of light-element substances contained in the object A, for example. Since the input surface 6a of the scintillator 6 is parallel to the transport direction D and parallel to the line direction d2 of the line scan camera 3, different parts of the object A (for example, the upstream end and the downstream end in the transport direction D) etc.), the magnification does not change. For example, as shown in FIG. 6B, if the input surface 6a has an angle with respect to the transport direction D, the radiographic image IMG2 will be blurred during the TDI integration due to the difference in magnification of the X-ray projection image. (See FIG. 6(d)). In this embodiment, as shown in FIG. 6(a), the input surface 6a is parallel to the transport direction D, so that the radiation image IMG1 is prevented from being blurred (see FIG. 6(c)). Furthermore, since the magnifying power does not change and the first mirror 7 is positioned outside the radiation irradiation area 12, the radiation that has passed through the object A enters the scintillator 6 without passing through the first mirror 7. Input to surface 6a. This eliminates the influence of the first mirror 7 on the radiation. That is, the scintillation light output from the input surface 6a of the scintillator 6 can be detected without being affected by the first mirror 7. FIG. As a result, the radiographic image acquisition system 1 and the imaging unit 30 make it possible to acquire a clear and highly sensitive radiographic image of an object. Moreover, according to the radiographic image acquisition system 1, a radiographic image can be acquired at a higher speed. Furthermore, a radiographic image with a good S/N ratio can be obtained.

Further, when the scintillator surface observation method is used, it is possible to image the light-reducing element under a high tube voltage. The radiation source 2 has a characteristic that the output of tube voltage and tube current is restricted, and in the case of a low tube voltage, it is difficult to obtain an output due to the restriction of tube current. By using the scintillator surface observation method, it is possible to perform X-ray imaging at a place where the radiation source 2 is efficient, because the tube current is less likely to be restricted. As a result, an improvement in tact time can be expected.

The line scan camera 3 detects scintillation light output in the normal B direction of the input surface 6a. As shown in FIG. 7B, when scintillation light output in a direction inclined with respect to the normal B direction of the input surface 6a is detected, TDI integration is A perspective is generated in the radiographic image IMG4 by (see FIG. 7(d)). In that case, radiographic image IMG4 will be blurred. On the other hand, as shown in FIG. 7A, when the line scan camera 3 detects scintillation light output in the normal B direction of the input surface 6a, perspective does not occur in the radiation image IMG3. (See FIG. 7(c)). As a result, a clear radiographic image IMG3 is obtained. By the way, in order for the line scan camera 3 to photograph the input surface 6a without interfering with the transport stage, it is necessary to secure a distance between the input surface 6a and the transport stage as shown in FIG. 7(a). It seems. Then, it is necessary to secure a difference between FDD (Focus-Detector Distance; distance from focal point 2a to scintillator 6) and FOD (Focus-Object Distance; distance from focal point 2a to object A). However, when the distance between the input surface 6a and the object A increases, the X-ray geometric magnification increases, and the X-ray projection image is enlarged. As the magnification increases, the effect of defocus also increases. Therefore, it is desirable to make the enlargement ratio as close to the same magnification (1 time) as possible. In this embodiment, the first mirror 7 is interposed to reduce the distance between the input surface 6a and the object A, and the scintillation light output in the normal B direction of the input surface 6a is emitted by the line scan camera 3. detected. Therefore, the line scan camera 3 can acquire an image without perspective. The radiographic image is prevented from being blurred.

The slit 15 is located between the scintillator 6 and the first mirror 7 and the line scan camera 3 in the transport direction D. As shown in FIG. From another point of view, the radiation source 2 is configured such that the focal point 2a is located between the first virtual plane P1 including the reflecting surface 7a of the first mirror 7 and the second virtual plane P2 including the input surface 6a of the scintillator 6. are placed in These arrangements allow the radiation to be successfully introduced within the acute angle between the scintillator 6 and the first mirror 7 . That is, the irradiation area 12 can be well formed within the acute angle range between the scintillator 6 and the first mirror 7 . On the other hand, it is easy to secure the optical path length required for the line scan camera 3 .

As shown in FIG. 8(a), the input surface 6a of the scintillator 6 and the transport direction D are required to be parallel. detection is required. Moreover, it is desirable to reduce the distance between the object A and the input surface 6a as much as possible. As a result, the first mirror 7 is adopted. However, as shown in FIG. 8B, when the first mirror 7 is installed, the first mirror 7 covers the irradiation area 12 of X-rays. As a result, soft X-ray components contained in X-rays are attenuated. As a result, low-energy radiation sensitivity is compromised. As a solution, the position and angle of the irradiation area 12 are adjusted so that the X-ray irradiation area 12 does not cover the first mirror 7, as shown in FIG. 8(c). For example, the positions of the radiation source 2 and the slit 15 are adjusted so that the central axis L of the irradiation area 12 is 45 degrees with respect to the input surface 6a.

The acute angle between the scintillator 6 and the first mirror 7 is within the range of 40 degrees or more and 50 degrees or less. According to this configuration, the scintillation light output in the normal B direction of the input surface 6a is reflected by the first mirror 7 and detected by the line scan camera 3 with an inclination angle of 10 degrees or less with respect to the transport direction D. be. Therefore, it is easy to install the line scan camera 3 along the conveying device 20 . The entire imaging unit 30 has a slim shape along the conveying device 20, and the imaging unit 30 can be made compact. When the acute angle is 45 degrees, this effect is exhibited even more favorably.

The irradiation area 12 is formed downstream of the scintillator 6 in the transport direction D. As shown in FIG. According to this configuration, it is easy to form the irradiation area 12 so that the first mirror 7 does not interfere with the radiation irradiation area 12 while the first mirror 7 is arranged at a desired position.

The optical axis F of the line scan camera 3 is parallel to the transport direction D. As shown in FIG. The input surface 6a of the scintillator 6 is parallel to the transport direction D, as described above. This configuration eliminates the need for complicated adjustments related to angles for each element. For example, adjustment of the optical axis F of the line scan camera 3 and adjustment of the distance between the first mirror 7 and the lens according to the viewing angle associated with the focal length of the lens of the line scan camera 3 are facilitated.

Subsequently, radiation image acquisition systems 1A and 30A according to the second embodiment will be described with reference to FIG. The radiation image acquisition system 1A is different from the radiation image acquisition system 1 of the first embodiment in that the imaging unit 30A is installed in the housing 13A and emits scintillation light from the rear surface 6b opposite to the input surface 6a. The point is that a second line scan camera 4 for detecting is further provided. The scintillator holder 8 is open upward and downward to expose the input surface 6a and the back surface 6b of the scintillator 6 . The second line scan camera 4 has a configuration similar to that of the line scan camera 3 . That is, the second line scan camera 4 has a lens section 4a and a sensor section 4b including an image sensor 4c. The third mirror 17 is held, for example, by a mirror holder 19 and arranged so as to be inclined with respect to the horizontal. The third mirror 17 is arranged at a position overlapping the normal line C of the back surface 6b so that the reflecting surface 17a faces the back surface 6b obliquely. The optical axis G of the lens portion 4a of the second line scan camera 4 is parallel to the transport direction D, for example. The second line scan camera 4 detects the scintillation light output in the direction of the normal line C of the back surface 6b via the reflecting surface 17a of the third mirror 17 . The position of the second line scan camera 4 in the transport direction D is set, for example, so that the optical path length in the line scan camera 3 and the optical path length in the second line scan camera 4 are equal. When using the same lens, for example, when using lenses having the same focal length, it is preferable to set the optical path lengths to be equal. On the other hand, when using different lenses, eg, lenses with different focal lengths, the optical path lengths are not necessarily equal.

Various aspects may be employed when using two cameras. For example, the second line scan camera 4 and the line scan camera 3 (first line scan camera) may be independently controlled as two cameras. The second line scan camera 4 and the line scan camera 3 may share a control board or the like so that two sensors can be controlled from one control system. If the line scan camera 3 and the second line scan camera 4 have different fields of view, alignment may be performed by image processing. When the line scan camera 3 and the second line scan camera 4 have different angles of view, alignment may be performed by image processing including coordinate conversion. If the number of pixels differs between the line scan camera 3 and the second line scan camera 4, the pixels may be matched by coordinate conversion or enlargement/reduction. When the line scan camera 3 and the second line scan camera 4 have different numbers of acquired lines due to different exposure times, etc., the numbers of lines may be made equal by interpolation, averaging, or thinning. When the line scan camera 3 and the second line scan camera 4 have different enlargement ratios, the enlargement ratio correction processing may be performed to match the enlargement ratios. If the line scan camera 3 and the second line scan camera 4 have different image sensors, correction processing may be performed to match the number of pixels.

In a region close to the back surface 6b of the scintillator 6, relatively high-energy radiation is converted. A line scan camera 3 acquires a low energy radiographic sensitive radiographic image, while a second line scan camera 4 simultaneously acquires a high energy radiographic image. This realizes a dual-energy imaging unit. Such a scintillator double-sided observation method can obtain a larger energy difference than a conventional dual energy unit, and improves foreign matter detection performance. This imaging unit 30A is excellent in discrimination performance of, for example, light element substances (hair, vinyl, insects, etc.).

Although the embodiments of the present disclosure have been described above, the present invention is not limited to the above embodiments. The invention may include various modifications.

For example, as shown in FIG. 10, as a first modification of the second embodiment, a scintillator double-sided observation type imaging unit 30B having a vertical housing 13B may be provided. In this imaging unit 30B, a first mirror 7 and a second mirror 7B, which are two mirrors for reflecting the scintillation light output in the normal B direction of the input surface 6a, are installed. Further, a third mirror 17 and a fourth mirror 17B, which are two mirrors for reflecting the scintillation light output in the normal C direction of the back surface 6b, are installed. This form can also be implemented in a two-sensor, one-lens system, which will be described later.

As shown in FIG. 11, as a second modification of the second embodiment, a scintillator double-sided observation type imaging unit 30C having a vertical housing 13C may be provided. In this imaging unit 30B, a first mirror 7 and a second mirror 7C, which are two mirrors for reflecting the scintillation light output in the normal B direction of the input surface 6a, are installed. Both the first mirror 7 and the second mirror 7C are located outside the illumination area 12 . The inclination angle θ1 of the central axis L of X-rays is, for example, 45 degrees. There is no mirror for reflecting the scintillation light output in the direction of the normal line C of the back surface 6b, and the second line scan camera 4 is arranged at a position overlapping the normal line C. As shown in FIG. In this form, the distance from the upper wall portion 13a of the housing 13 is short.

As shown in FIG. 12, as a third modification of the second embodiment, a scintillator double-sided observation type imaging unit 30D having a horizontal housing 13D may be provided. In this image pickup unit 30D, the line scan camera 3 and the second line scan camera 4 are installed diagonally below in the housing 13D. The tilt angle of the first mirror 7 is, for example, 30 degrees to 40 degrees. The tilt angle of the third mirror 17 is, for example, 50 degrees to 60 degrees. The inclination angle θ1 of the central axis L of X-rays is, for example, 45 degrees. The tilt angle of the first mirror 7 is set to the lowest angle that does not vignet X-rays, and is smaller than 45 degrees.

As shown in FIG. 13, as a first modification of the first embodiment, a radiation image acquisition system 1E may be provided in which an imaging unit 30 is attached to a conveying device 20 installed obliquely. In some existing inspection apparatuses, the radiation source 2 is installed horizontally and the transport device 20 is installed obliquely. For example, the object A freely falls on the conveying surface 21a, which is a sliding surface. In such a case, the imaging unit 30 can also be installed obliquely. In this manner, the imaging unit 30 can be installed at any angle and in any orientation, and can be easily incorporated into existing inspection apparatuses. The versatility of the imaging unit 30 is enhanced. In this radiation image acquisition system 1E, the slit 15 is positioned upstream of the scintillator 6 in the transport direction D, for example. Note that a double-sided observation method may be applied to the oblique transport type radiographic image acquisition system 1E shown in FIG.

As shown in FIG. 14, as a further modification applied to the oblique transport shown in FIG. 13, a housing 13F may be provided in which only the scintillator 6 and the first mirror 7 are obliquely shaped. In this imaging unit 30F, two mirrors, a first mirror 7 and a second mirror 7F, are installed inside a housing 13F. The scintillation light can be taken out horizontally by the first mirror 7 and the second mirror 7F. The line scan camera 3 is arranged horizontally. According to this imaging unit 30F, for example, the housing in which the line scan camera 3 is installed can be horizontally installed, and the X-rays from the radiation source 2 can also be emitted vertically (vertically). Although the object A is conveyed obliquely, there is an advantage that the oblique section can be shortened. Note that the double-sided observation method may be applied to the oblique transport type and horizontal installation type imaging unit shown in FIG. 14 .

The form in which the imaging unit is installed obliquely can be effectively applied to, for example, a transport device that releases the object A into the air.

A multi-lens multi-sensor camera may be applied instead of the line scan camera 3 or the second line scan camera 4 in each of the above embodiments. That is, instead of one high-resolution camera, multiple low-pixel cameras can be used. By reducing the pixels of the sensor, the distance between the scintillator 6 and the camera can be reduced. As a result, the size of the entire housing can be reduced.

As shown in FIG. 15, two cameras 25A and 25B may be installed in parallel. For example, the two cameras 25A and 25B are arranged in a direction orthogonal to the transport direction D. A common main board 26 is connected to each of the camera boards 25a and 25b of the cameras 25A and 25B. According to this form, high resolution can be obtained, and the size of the housing can be suppressed. The number of cameras arranged in parallel may be three or more. Two high resolution cameras may be used in parallel, or one or more low resolution cameras and one or more high resolution cameras may be used. For example, if two cameras are arranged side by side, the pixel pitch can be halved, and if three cameras are arranged side by side, the pixel pitch can be reduced to one third.

Also, as shown in FIG. 16(a) or FIG. 16(b), a one-lens, two-sensor camera may be applied. That is, two TDI sensors (or line sensors) 28, 28 are arranged within one image circle. In this case, only one lens is required, which can be advantageous in terms of cost or size. If the focal length L1 is fixed, the distance L2 must be increased in order to widen the detection width. The distance L3 between 7 and 17 is also increased. On the other hand, there is a limit to the distance L4 between the sensors 28,28.

A method of performing stop-and-go imaging using an area sensor instead of the TDI sensor is also conceivable. For example, as shown in FIG. 17, one sensor 29 may be provided with a low energy fluorescent image area 29a and a high energy fluorescent image area 29b. By cutting out and tiling arbitrary regions 29a and 29b, a low-energy radiographic image and a low-high-energy radiographic image can be captured. According to this method, imaging with one lens and one sensor is possible.

Moreover, various modifications are conceivable for the scintillator holder 8 or the mirror holder 9 as well. As shown in FIG. 18, an adjustment mechanism 35 may be installed that can adjust the positions of the first mirror 7 and the third mirror 17 with respect to the scintillator 6 . This adjustment mechanism 35 is connected to, for example, the mirror holder 9 of the first mirror 7 and the mirror holder 19 of the third mirror 17 so that the first mirror 7 and the third mirror 17 are aligned in the normal B direction of the input surface 6a and the back surface 6b. are moved along the normal line C direction of . Thereby, the height of the scintillation light can be arbitrarily changed. The first mirror 7 and the third mirror 17 may interlock and move symmetrically with respect to the scintillator 6, or the first mirror 7 and the third mirror 17 may move separately.

Alternatively, the first mirror 7 and the third mirror 17 may be fixed to a common mirror unit holder 36 as shown in FIGS. 19(a) and 19(b). By preparing a mirror unit holder 36 with a relatively small distance in the directions of the normals B and C and a mirror unit holder 37 with a relatively large distance in the directions of the normals B and C, and exchanging them , the height of the scintillation light can be changed.

Further, as shown in FIGS. 20(a) and 20(b), an adjustment mechanism 38 is installed which can adjust the positions of the first mirror 7 and the third mirror 17 with respect to the scintillator 6 by moving the scintillator holder 8 back and forth. may be As shown in FIG. 21, for example, a scintillator 6A that is elongated in the transport direction D is held by a scintillator holder 8, and the radiation irradiation position (the position of the central axis L in the figure) is changed in the transport direction D, whereby the scintillator The positions of the first mirror 7 and the third mirror 17 with respect to 6 may be adjusted. In this case, the positional relationship (distance) between the scintillator 6 and the first mirror 7 and the third mirror 17 can be steplessly and flexibly changed.

As shown in FIGS. 22(a) and 22(b), a mechanism for changing the position of the slit 15, which is the radiation entrance window, may be provided. For example, a relatively large opening 45 may be formed in the upper wall portion 13a of the housing 13A, and an adjustment plate 47 having a slit 15 smaller than the opening 45 may be installed. In this case, the adjustment plate is part of the wall of housing 13A. The adjustment plate 47 is fixed to the upper wall portion 13a with, for example, four screws 46 positioned at the four corners. Four elongated holes 47a are formed in the adjustment plate 47 in the transport direction D, and screws 46 are inserted through these elongated holes 47a. The adjustment plate 47 can change its position in the transport direction D within the range of the long hole 47a.

As described above, the means for physically changing the distance between the scintillator 6 and the first mirror 7 and the third mirror 17 and the means for changing the relative positions of the scintillator 6 and the first mirror 7 and the third mirror 17 means for changing the distance by

Further, as shown in FIG. 23, a plurality of holding holes 50 are formed in the bottom wall portion 13b of the housing 13A, and by engaging the pins 49 in the holding holes 50, the second line scan camera is 4 (and line scan camera 3) in the transport direction D may be adjusted. The distances between the first and third mirrors 7 and 17 and the line scan camera 3 and second line scan camera 4 change depending on the focal length of the camera and the length of the scintillator 6 . The position of the camera can be easily adjusted for multiple lenses (focal lengths) and the length of the scintillator 6 .

The line scan camera and the second line scan camera are not limited to including the TDI sensor. The linescan camera and the second linescan camera may include one or more linescan sensors. That is, processing similar to time delay integration may be performed using a multiline sensor having two or more multiple columns, or an image such as a line sensor image may be obtained by reading the signal of each line of the multiline sensor and performing signal processing. may be created. Images may be created using a single line sensor. Even a single-line sensor is subject to magnification within a pixel, which can result in blurred images. When affected by the magnification factor, the fluorescence image can move diagonally within the pixel, causing a loss of resolution and blurring of the image. According to the radiographic image acquisition system and the imaging unit of the present disclosure, blurring of the radiographic image can be prevented.

Digital signal summation of the photodiode array may be performed. The need for tight speed matching is alleviated when using a multistage photodiode array. If a photodiode array is used, the detection section may be oblique. That is, the input surface 6a does not have to be parallel to the transport direction D. By performing image processing such as addition or averaging after performing magnification correction and line delay, it is possible to obtain the effects aimed at by the radiation image acquisition system of the present disclosure.

The irradiation area 12 of radiation is not formed by the slit 15 of the housing 13, but an irradiation area defining section composed of a plurality of shielding walls (or shielding plates) is installed between the radiation source 2 and the scintillator 6. may In that case, a radiation source 2 with a wide irradiation angle or output area 14 may be used.

DESCRIPTION OF SYMBOLS 1, 1A, 1E... Radiation image acquisition system, 2... Radiation source, 2a... Focal point, 3... Line scan camera, 6... Scintillator, 6a... Input surface, 6b... Back surface, 7... First mirror, 12... Irradiation area, 13, 13A, 13B, 13C, 13D, 13F... Case, 13a... Upper wall (wall), 15... Slit, 15a... Periphery, 20... Conveying device, 30, 30A, 30B, 30C, 30D, 30F... Imaging unit, A... Object, B... Normal line, C... Normal line, F... Optical axis, G... Optical axis, P... Transport path.

Claims (6)

A radiographic image acquisition system for acquiring a radiographic image of an object,
a conveying device that conveys the object on the conveying path in the conveying direction;
a radiation source that outputs radiation toward the object from a direction that is inclined with respect to the transport direction;
a slit through which the radiation that has passed through the object passes;
a scintillator having an input surface into which the radiation is input, and arranged so that the radiation that has passed through the slit is input in a direction inclined with respect to the input surface;
and a line scan camera that captures scintillation light output from the scintillator. Further comprising a housing arranged to face the transport path and having the slit,
2. The radiation image acquisition system according to claim 1, wherein said scintillator and said line scan camera are arranged within said housing. 3. The radiation image acquisition system according to claim 1, further comprising a first reflecting mirror that reflects the scintillation light output from the input surface of the scintillator toward the line scan camera. 4. The radiation image acquisition system according to claim 1, further comprising a second reflecting mirror that reflects the scintillation light output from the back surface of the scintillator toward the line scan camera. An imaging unit for acquiring a radiographic image of an object,
a housing having a slit through which radiation passes;
a scintillator having an input surface into which the radiation is input and arranged in the housing so that the radiation that has passed through the slit is input in a direction that is inclined with respect to the input surface;
a line scan camera that is arranged in the housing and captures scintillation light output from the scintillator;
and a first reflecting mirror that reflects the scintillation light output from the input surface of the scintillator toward the line scan camera. 6. The imaging unit according to claim 5 , further comprising a second reflecting mirror that reflects the scintillation light output from the back surface of the scintillator toward the line scan camera.

Images